| Moores of Warwick Limited | Manufacturing | 2017 |
| Moorhill Cabs Limited | Transport & logistics | 2023 |
| Morgan-Young Limited | Information & communication | 2018 |
| Morgen Thomas Limited | Professional & scientific | 2011 |
| Morvidus Security UK Ltd | Administrative & support | 2024 |
| Moseley Lodge Management Company Ltd | Households | 2019 |
| Moss & Ember Ltd | Wholesale & retail | 2025 |
| Motion Drives (Holdings) Limited | Financial services | 2022 |
| Motion Drives and Controls Limited | Manufacturing | 1992 |
| Motoart Limited | Wholesale & retail | 2021 |
| Motodan Limited | Professional & scientific | 2015 |
| Motor Hub Warwick Ltd | Transport & logistics | 2019 |
| Motor Investments (Oxford) Limited | Real estate | 1974 |
| Motorclimate UK Limited | Manufacturing | 2001 |
| Motorway Tyres (Luton) Limited | Wholesale & retail | 1966 |
| Mountford Contract Services Ltd | Professional & scientific | 2024 |
| Mountford Mews Limited | Construction | 2024 |
| Moztek Solutions Ltd | Construction | 2025 |
| MP Consultancy Ltd | Professional & scientific | 2021 |
| MPI Living Limited | Hospitality | 2020 |
| Mployability Ltd | Administrative & support | 2022 |
| Mpopescu Automotive Ltd | Professional & scientific | 2026 |
| MR & MRS Wood Ltd | Real estate | 2026 |
| MR B'S Kitchen Ltd | Hospitality | 2024 |
| MR Christopher Jonathan Clarke Ltd | Extraterritorial | 2025 |
| Mrs.Crustyloaf Ltd | Hospitality | 2023 |
| MS Brown Properties Ltd | Households | 2019 |
| MSP Consultants Limited | Information & communication | 2013 |
| MTS Property Management Ltd | Real estate | 2023 |
| Muddy Puddles Playgroup Limited | Education | 2021 |
| Multitech Engineering Limited | Professional & scientific | 1992 |
| Mundo Livre Digital Limited | Information & communication | 2021 |
| Munro Business Park Limited | Real estate | 2018 |
| Munster Joinery (U.K.) Limited | Construction | 1996 |
| Murphy & Co Hospitality Limited | Hospitality | 2024 |
| MWA Group Holdings Limited | Financial services | 2022 |
| MWA Technology Limited | Wholesale & retail | 2008 |
| Mwlt Property LLP | | 2025 |
| MWO Contracting Limited | Construction | 2025 |
| My Health Tests Limited | Health & social care | 2022 |
| My Heavenly Limited | Wholesale & retail | 2025 |
| My PSA Tests Limited | Health & social care | 2020 |
| My Time Housing Ltd | Real estate | 2020 |
| Mygradapp Limited | Information & communication | 2024 |
| Myndscan London Limited | Health & social care | 2022 |
| Myndspan Limited | Health & social care | 2020 |
| Mytax Limited | Professional & scientific | 2007 |
| Myton Gables Limited | Real estate | 2016 |
| Myton Hamlet Hospice Development Limited | Construction | 1995 |
| Myton Planning & Development Limited | Professional & scientific | 2016 |
| Myton Property Group Limited | Real estate | 2019 |
| Myton School Trust | Education | 2011 |
| N & M Consultancy Limited | Information & communication | 1991 |
| N & P Properties Limited | Real estate | 2017 |
| N E Gilbert Developments Limited | Construction | 2014 |
| N T Barrett Plumbing & Heating Ltd | Construction | 2010 |
| N U Huda Ltd | Health & social care | 2023 |
| N&E Innovations Limited | Administrative & support | 2026 |
| N1U Limited | Financial services | 2023 |
| Nabo Bains Ltd | Real estate | 2024 |
| NAC Boutique Living Limited | Real estate | 2025 |
| Nahil & Bhangal Developments Limited | Real estate | 2021 |
| Najell UK Limited | Wholesale & retail | 2025 |
| Najingham Limited | Health & social care | 2022 |
| Nashwhite Projects Limited | Financial services | 2023 |
| Nashwhite Research & Development Limited | Other services | 2023 |
| Nashwhite Stratford Upon Avon Limited | Other services | 2023 |
| Nashwhite the Heist House Limited | Other services | 2023 |
| Natalie Alexander Ltd | Manufacturing | 2026 |
| Natalie Christopher Estate Agents Limited | Real estate | 2023 |
| Nathean Technologies UK Limited | Administrative & support | 2011 |
| National Asbestos Surveys Limited | Professional & scientific | 2025 |
| National Data Centre Academy Limited | Information & communication | 2016 |
| National Electric & Engineering Ltd | Construction | 2023 |
| National GAS Metering Limited | Energy | 1999 |
| National GAS Transmission Holdings Limited | Professional & scientific | 1998 |
| National GAS Transmission Pension Scheme Nominee Company One Limited | Professional & scientific | 2023 |
| National GAS Transmission Pension Scheme Nominee Company Two Limited | Professional & scientific | 2023 |
| National GAS Transmission Pension Trustee Limited | Professional & scientific | 2022 |
| National GAS Transmission PLC | Energy | 1986 |
| Nationwide Data Collection (London) Ltd | Professional & scientific | 2008 |
| Nationwide Data Collection (Scotland) Limited | Professional & scientific | 2009 |
| Nationwide Data Collection Limited | Professional & scientific | 2007 |
| Nationwide Drones Ltd | Professional & scientific | 2018 |
| Natural Green Creative Spaces Ltd | Administrative & support | 1996 |
| Natural Resources Global Capital Group Limited | Financial services | 2014 |
| Natural Resources Global Capital Partners Limited | Financial services | 2011 |
| Naturall Carbon Limited | Professional & scientific | 2022 |
| Naturally Dippy Ltd | Hospitality | 2021 |
| Nawapower Ltd | Professional & scientific | 2024 |
| Nazar Wholesale Limited | Wholesale & retail | 2014 |
| NBW Consultant Limited | Information & communication | 2025 |
| Ncab Group Kestrel Limited | Wholesale & retail | 1995 |
| Ncab Group UK Limited | Wholesale & retail | 2009 |
| Ncctc Limited | Administrative & support | 2016 |
| ND Advisory Services Limited | Professional & scientific | 2025 |
| NDA Corporation Ltd | Wholesale & retail | 2022 |
| Neacsu Trans Ltd | Transport & logistics | 2017 |
| Necoara Contractors Limited | Construction | 2025 |
| Need the LOO Toilet Hire Limited | Wholesale & retail | 2024 |